Newegg.com

This is a good link

You probably have a few local computer stores that will sell you exactly what you’re looking for at a very good price. 1gb sticks are dirt cheap. 2gb are very cheap. 4gb are cheap, 8gb are moderate in price (I paid $30 CDN a year ago for one). Do a google search for your town and “electronics” or “computer store” to find some in your area.

Here in Australia, you can get 4GB for ~AU$28. You won’t have any trouble. They’re only expensive if you’re looking at something 16GB or larger.